How sea spray affects cloud formation

Beyond the poetry of crashing ocean waves, salt- and carbon-rich sea spray has a dramatic effect on the formation and duration of clouds which cover 60 percent of the Earth's surface at any given time, says a study.

Sea spray is a unique, underappreciated source of what are called ice nucleating particles - microscopic bits that make their way into clouds and initiate the formation of ice, and in turn affect the composition and duration of clouds, said researcher Paul DeMott from Colorado State University in the US.

"The presence of these particles is critically important for precipitation and the lifetime of clouds, and consequently, for their radiative properties," DeMott said.

Clouds, with their ability to reflect solar energy and absorb terrestrial radiation, have dramatic effects on climate.

Their radiative properties are greatly influenced by the number, size and type of droplets and ice particles inside the cloud.

These cloud particles can initiate from any number of sources of aerosols - particles suspended in air - from land and ocean surfaces.

From desert dust to burning fossil fuels, aerosols that affect clouds are everywhere.

DeMott's study has confirmed that ice nucleating particles from oceans are distinct, both in their abundance as well as their ice-making properties, from land-sourced particles.

Hence, their influence on the liquid/ice phase structure of clouds, and their subsequent radiative impacts, can differ over vast swaths of Earth.

The study appeared online in the journal Proceedings of the National Academy of Sciences.